Solid transfer negative- or positive-working color proofing element

ABSTRACT

This invention provides an improved negative-working or positive-working, single sheet color proofing method which can accurately reproduce images by using colored, photosensitive layers on substrates which are then overcoated with partially developable adhesive layers. The final construction is useful in predicting the image quality from a lithographic printing process. The partial removal of the adhesive layers cleans out any background stain which may remain from the incomplete removal of the photosensitive layer.

This is a divisional of application Ser. No. 07/881,442 filed May 11,1992, which is a continuation of Ser. No. 07/261,374 filed Oct. 21,1988, U.S. Pat. No. 5,213,941 granted May 25, 1993.

BACKGROUND OF THE INVENTION

In the graphic arts, it is desirable to produce a three or more colorproof to assist in correcting a set of Color separation films prior tousing them to produce printing plates. The proof should reproduce thecolor quality that will be obtained during the printing process. Theproof must be a consistent duplicate of the desired halftone image.Visual examination of a color proof should show the color rendition tobe expected from press printing using the color separations and anydefects on the separations which might need to be altered before makingthe printing plates.

Color proofing sheets for multicolored printing can be made by using aprinting press or proof press. This requires that all of the actualprinting steps be performed. However, this conventional method of colorproofing is costly and time consuming.

Photoimaging processes can also be used to produce color proofs. Thereare two general types of photoimaging methods; namely the overlay typeand the single sheet type.

In the overlay type color proofing method, an independent transparentplastic support is used for producing an image of each color separationfilm by applying a photosensitive solution of the corresponding color. Aplurality of such supports carrying images of the corresponding colorsare then superimposed upon each other over a white sheet to produce acolor proofing composite. The primary advantage of the overlay method isthat proofs can be made quickly and can serve as a progressive proof bycombining any two or three colors in register. However, this type ofcolor proofing method has the disadvantage that the superimposed plasticsupports tend to darken the color proofing sheet. As a result, theimpression of the color proofing composite thus prepared is vastlydifferent from that of copies actually obtained with conventionalprinting presses and with proof presses. Examples of such overlayapproaches are contained in U.S. Pat. Nos. 3,136,637; 3,211,553; and3,326,682.

In the single sheet type of color proofing method, a color proofingsheet is prepared by successively producing images of different colorsfrom different color separation films onto a single receiver sheet. Thisis done by utilizing a single opaque support and by applying toners,transferring images, or processing solutions or coatings ofphotosensitive materials of corresponding colors on the opaque supportin succession. An advantage of the single sheet type of color proof isthat the color saturation is not influenced by superimposed plasticsupports. This method more closely resembles the actual printing processand eliminates the color distortion inherent in the overlay system.

The present invention relates to improved negative-working andpositive-working proofing sheets of the single sheet, solid layertransfer class. Color proofing films of this type are composed of asheet substrate, a colored photosensitive layer on the sheet, and anadhesive layer disposed on the photosensitive layer.

An example of a negative-working, single sheet approach is described inU.S. Pat. No. 3,671,236. The presensitized element comprises a substratehaving a release surface, a pigmented photosensitive layer in contactwith the release surface, a pressure sensitive adhesive layer, and abarrier layer between the photosensitive layer and the adhesive layer.The primary function of the barrier layer is to prevent pigment stainingon the adhesive during development. The element is used by laminating itto a receiver via the adhesive layer. The substrate is removed, thephotosensitive layer is exposed, and the material is processed in asolvent medium. These steps are generally repeated three times toproduce a multicolored proof.

An example of a positive-working, single sheet approach is given in U.S.Pat. No. 4,260,673. The presensitized element comprises a substratehaving a release surface, a pigmented photosensitive layer in contactwith the release surface, a heat sensitive adhesive layer, and a binderlayer between the pigmented layer and the adhesive layer. The binderlayer comprises a photosensitive compound and prevents pigment stainingof the adhesive. The element is processed like the negative-workingelement in U.S. Pat. No. 3,671,236.

Examples of negative-working and positive-working, single sheetapproaches without preventative layers between the photosensitive andadhesive layers are described in U.S. Pat. Nos. 4,650,738 and 4,659,642,respectively. The presensitized elements comprise a sheet having arelease surface, a colored photosensitive layer in contact with therelease surface, and an adhesive layer directly adhered to said coloredlayer. The adhesive layer comprises a vinyl acetate polymer.

This invention provides an improved photosensitive element whichprovides an adhesive layer which is partially removable by the liquiddeveloper. In this manner the uppermost part of the adhesive layer isremoved so that the layer retains its adhesive property but any residualphotosensitive layer which causes background staining is removed.

SUMMARY OF THE INVENTION

The present invention provides an improved photosensitive element andmethod for forming a colored image which comprises:

A. providing a photosensitive element which comprises, in order:

i) a substrate having a release surface; and

ii) a single, colored photosensitive layer on said release surface,which photosensitive layer comprises a light sensitive, negative-workingdiazonium salt or positive-working naphthoquinone diazide compound in anamount sufficient to photosensitize the layer; a resinous bindercomposition in an amount sufficient to bind the layer components into auniform film, which composition contains a major amount of at least oneresin selected from the group consisting of a vinyl acetal polymer and astyrene/maleic anhydride copolymer half ester; and at least one colorantin an amount sufficient to uniformly color the layer; and

iii) a nonphotosensitive adhesive layer in direct contact with saidphotosensitive layer, which adhesive layer comprises a major amount ofone or more thermoplastic polymers, is partially soluble in thedeveloper, is nontacky at room temperature, and can be transferred attemperatures between 60° C. and 180° C.; and

B. either

i) laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and removing saidsubstrate by the application of peeling forces; and imagewise exposingsaid photosensitive layer to actinic radiation; or

ii) imagewise exposing said photosensitive layer to actinic radiation;and laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and removing saidsubstrate by the application of peeling forces; or

iii) laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and imagewise exposingsaid photosensitive layer to actinic radiation; and removing saidsubstrate by the application of peeling forces; and

C. removing the nonimage areas of said photosensitive layer and some ofthe said adhesive layer with a liquid developer, which removing isconducted at a temperature at which said adhesive layer is substantiallynontacky; and

D. preferably repeating steps A through C at least once whereby anotherphotosensitive element having at least one different colorant islaminated onto said receptor sheet over the nonremoved portions of thepreviously laminated and processed photosensitive layer or layers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the production of the color proofing film of this invention, oneprovides a photosensitive element which broadly comprises a substratehaving a release surface, a colored photosensitive layer on the releasesurface, and an adhesive layer on the photosensitive layer. It ispreferred that the substrate is composed of a dimensionally andchemically stable base material which does not significantly change itssize, shape, or chemical properties as the result of the heating,coating, or other treatments which it must undergo. One especiallypreferred material is polyethylene terephthalate. In the usual case, ithas a thickness of from about 1 to about 10 mils, a more preferredthickness is from about 2 to about 5 mils, and most preferably fromabout 2 to about 3 mils. Suitable films include Hostaphan 3000 availablefrom Hoechst Celanese Corporation, Mylar D available from DuPont, andMelinex 516 available from ICI. The surface of the substrate may besmooth or may be provided with a matte texture by various methods knownin the art.

Matte films include Melinex 377 and 470 from ICI. These materials havethe unique property of giving the final image a desired matte finishwithout any extra steps. One can control the gloss of the final image byproperly selecting the matte finish of the temporary support. Thiseffect works because the top layer of the final image is originally incontact with this matte surface. An additional advantage of coating on amatte surface is that subsequent transferred layers generally adherebetter to a rough surface than to a smooth surface.

A similar matte finish of the final image can be obtained by embossingthe top surface of the image with a matte material, such as describedabove. This is done by laminating together the final image and mattematerial with heat and pressure. The matte material is then generallyremoved after lamination. The advantage of this method is that thefinish of the final proof can be varied. Furthermore, the mattingmaterial can be used repeatedly.

Another method for producing a matte finish uses a heat transferablelayer, such as Butvar 90 available from Monsanto, coated onto a filmwith a rough surface, such as Melinex 329 available from ICI. Thetransferable layer is laminated to the final image with heat andpressure. Then the film with the rough surface is peeled off. The roughsurface of the transferred layer imparts a matte finish to the finalimage. An additional advantage is that the extra transferred layerprotects the image. U.S. Pat. Nos. 4,294,909 and 4,376,159 also suggestvarious methods for making a matte surface. The substrate must have arelease surface, that is, it must be capable of releasably holding thephotosensitive layer thereto. This may be accomplished by the substratesurface being either inherently releasable, rendered releasable by asuitable treatment, or provided with a release layer over the substratesurface. Such a release layer may comprise polyvinyl alcohol.

Releasably bonded to the release surface is the photosensitive layer.The photosensitive layer broadly comprises a photosensitizer, acolorant, a binding resin, and other optional ingredients such asplasticizers, acid stabilizers, surfactants, antistatic compositions, uvabsorbers, optical brighteners, inert fillers, and residual coatingsolvents.

The preferred negative-working photosensitizer is a light sensitive,polymeric diazonium salt. The most preferred photosensitizer is thepolycondensation product of 3-methoxy-4-diazo-diphenylamine sulfate and4,4'-bis-methoxymethyl-diphenyl ether, precipitated as mesitylenesulfonate as taught in U.S. Pat. No. 3,849,392. Other suitablephotosensitizers are taught in U.S. Pat. No. 4,436,804. The diazocompounds of choice are preferably soluble in organic solvents.

The preferred positive-working photosensitizer is a light sensitive,naphthoquinone diazide. The most preferred photosensitizer is the esterof bis-(3-benzoyl-4,5,6-trihydroxy phenyl)-methane and2-diazo-1-naphthol-5-sulfonic acid as taught in U.S. Pat. No. 4,407,926.Other suitable photosensitizers are taught in U.S. Pat. Nos. 3,106,365;3,148,983; 3,201,239; and 4,266,001. The diazo compounds of choice arepreferably soluble in organic solvents.

Suitable binding resins for the photosensitive layer include polyvinylbutyral, styrene maleic anhydride copolymer half esters, and mixturesthereof. Such resins include Butvar B72, B76 and B90, and Scripset 540and 550, all available from Monsanto. An important resin selectioncriterion is that it must be a good film former.

The colorants useful for the present invention include various classesof dyes and pigments. Preferred colorants for this invention arepigments rather than dyes. In the most preferred embodiment, pigmentshaving an average particle size of about 1 micrometer or less are used.Nonexclusive examples of pigments usable in the present invention are asfollows: Permanent Yellow G (C.I. 21095), Permanent Yellow GR (C.I.21100), Permanent Yellow DHG (C.I. 21090), Permanent Rubine L6B (C.I.15850:1), Permanent Pink F3B (C.I. 12433), Hostaperm Pink E (73915),Hostaperm Red Violet ER (C.I. 46500), Permanent Carmine FBB (12485),Hostaperm Blue B2G (C.I. 74160), Hostaperm Blue A2R (C.I. 74160), andPrintex 25. Most of these are products of Hoechst AG. They can be usedseparately or blended for a desired color.

Optional plasticizers which may be incorporated into the photosensitivelayer include those of the phthalate and phosphate types. Preferredplasticizers include dibutyl phthalate and dimethyl phthalate. Acidstabilizers include phosphoric acid and p-toluene sulfonic acid.

The photosensitive layer ingredients may be blended with such compatiblesolvents as ethanol, methyl cellosolve, gamma butyrolactone, propyleneglycol monomethyl ether, and methyl ethyl ketone. The solution is thencoated on the release surface of the substrate. The photosensitive layerhas a preferred coating weight of between approximately 0.1 and 5.0g/m². The most preferred weight is from about 0.5 to 2.0 g/m².

In the preferred embodiment, the photosensitizer is present in thephotosensitive layer in an amount of from about 5 to about 70 percent byweight; or more preferably from about 10 to about 50 percent by weight.

In the preferred embodiment, the colorant is present in thephotosensitive layer in an amount of from about 5 to about 50 percent byweight; or more preferably from about 10 to about 40 percent by weight.

In the preferred embodiment, the binding resin is present in thephotosensitive layer in an amount of from about 10 to about 80 parts byweight; or more preferably from about 20 to about 70 parts by weight.

    ______________________________________                                                        Cyan Yellow  Magenta  Black                                   ______________________________________                                        Typical formulations by weight for the negative-working                       photosensitive layer includes:                                                methyl cellosolve 41.00  41.00   46.50  41.00                                 methyl ethyl ketone                                                                             41.00  40.99   46.48  41.00                                 gamma-butrylactone                                                                              10.00  10.00   --     10.00                                 dimethyl phthalate                                                                              0.75   0.75    0.88   0.75                                  dibutyl phthalate 0.25   0.25    --     0.25                                  p-toluene sulfonic acid                                                                         --     --      0.18   0.35                                  Scripset 540      3.33   2.60    3.15   3.71                                  Scripset 550      1.17   --      --     --                                    hydrolyzed Scripset 540                                                                         --     --      0.67   --                                    SMA 2625          --     2.02    --     --                                    Above diazo from US 3,849,392                                                                   1.33   1.35    0.70   2.00                                  phthalo blue pigment                                                                            1.17   --      --     --                                    yellow pigment    --     1.04    --     --                                    magenta pigment   --     --      1.44   --                                    black pigment     --     --      --     0.94                                  optical density   1.1    0.9     1.2    1.5                                   Typical formulations by weight for the positive-working                       photosensitive layer include:                                                 diacetone alcohol --     11.74   --     --                                    methyl ethyl ketone                                                                             35.52  34.45   24.23  38.62                                 gamma butyrolactone                                                                             22.60  11.15   24.04  5.74                                  Dowanol PM        34.76  35.21   44.94  48.34                                 Scripset 540      1.60   2.01    2.15   2.39                                  SMA 2625          1.74   1.17    --     0.60                                  Butvar B-90       0.58   0.59    0.67   0.30                                  Above diazo from US 4,407,426                                                                   2.Q9   2.58    2.81   2.72                                  phthalo blue pigment                                                                            1.11   --      --     --                                    yellow pigment    --     1.08    --     --                                    magenta pigment   --     --      1.15   --                                    black pigment     --     --      --     1.29                                  optical density   1.2    1.0     1.4    1.6                                   ______________________________________                                    

Scripset and Butvar resins are from Monsanto, SMA resin is from Arco,and Dowanol PM is propylene glycol monomethyl ether from Dow.

The adhesive layer comprises a major amount of one or more thermoplasticpolymers. Suitable polymers nonexclusively include vinyl butyral resinssuch as Butvar B-79 available from Monsanto; acrylic resins such asElvacite 2044 available from DuPont; ethylene resins such as Elvax 210;available from Dupont; vinyl chloride resins such as Hostaflex CM 133available from Hoechst AG; and phenolic resins such as Alnovol PN 429available from Hoechst AG. The adhesive layer must be partially solublein the developing medium. Preferably between about 0.1% and 30% of theadhesive layer is removed during development. More preferably betweenabout 0.1% and 10% of the adhesive layer is removed. Generally,thermoplastic polymers suitable for this application are not soluble inthe developing medium. Therefore, developing aids must be incorporatedinto the adhesive layer. Suitable developing aids nonexclusively includeacrylic resins with high acid numbers of about 8 or more, such asCarboset 525 available from BF Goodrich; methyl vinyl ether/maleicanhydride copolymers such as Gantrez AN-119 available from GAF; andvinyl pyrrolidone resins such as PVP K-30 also available from GAF. Theamount of developing aid is less than 50% of the adhesive layer,preferably less than 30%.

The ingredients for the adhesive layer are generally dissolved in asuitable solvent or solvent mixture which does not change the functionalnor colorimetric characteristics of the colored, photosensitive layer.The solutions are then coated directly on the photosensitive layer. Itis then dried to a coating weight of from about 3 to about 30 g/m², ormore preferably from about 5 to about 20 g/m². The layer may optionallycontain a uv absorber such as Uvinul D-50 from GAF. It may also containa plasticizer such as Resoflex R-296, available from CambridgeIndustries. It may also contain antistats, such as Gafac and Gafstatfrom GAF. The adhesive layer should not be tacky to the touch, duringstorage or during development of the photosensitive element. The layershould be transferable in the range of from about 60° C. to about 180°C., or preferably 60° C. to 120° C., or more preferably 60° C. to 100°C. when laminated with heat and pressure.

Typical adhesive formulations by weight include:

    ______________________________________                                        I.         toluene      4                                                                n-butyl acetate                                                                           82                                                                Butvar B-79 10                                                                Gantrez AN-119                                                                            14                                                     II.        n-butyl acetate                                                                           83                                                                UCAR VYNC   15                                                                Carboset 525                                                                               2                                                     ______________________________________                                    

In operation, the photosensitive element is laminated to a receiversheet via the adhesive layer. The receiver sheet should be resistant toany adverse effects which may be caused by the developer of choice andlaminating procedure. For example, the receiver sheet should be waterresistant if aqueous developers are used and dimensionally stable underthe elevated temperature and pressure conditions during lamination.Plastic or plastic coated receiver sheets are useful for this purpose.

Useful receiver sheets include Melinex 329, 339, 994 and 3020 availablefrom ICI. Other white and nonwhite receiver sheets may also be used.Rough textured and/or adhesion promoted surfaces are preferred for thereceiver.

Lamination may be conducted by putting the receiver sheet in contactwith the adhesive side of the colored composite and then introducing thetwo materials into the nip of a pair of heated laminating rollers undersuitable pressure. Suitable laminating temperatures usually range fromabout 60° C. to about 180° C., preferably about 60° C. to about 120° C.After lamination, the substrate is peeled away, usually merely employingmanual peeling forces. The adhesive and photosensitive layers thusremain on the receiver sheet.

The photosensitive layer is imagewise exposed by means well known in theart either before or after lamination. Such exposure may be conducted byexposure to a uv light source through a color separation under vacuumframe conditions. Exposures after lamination and peel apart arepreferred for photosensitive-to-emulsion contact. Mercury vapordischarge lamps are preferred over metal halide lamps. Other radiationsources, such as carbon arc, pulsed xenon, and lasers, may also be used.Light absorbing filters may be used to reduce light scattering in thematerial.

After lamination, substitute removal, and exposure, the photosensitivelayer is developed by dissolving the nonimage area in a suitabledeveloper and dried. The adhesive layer is partially removed by thisdevelopment. A suitable developer nonexclusively includes:

    ______________________________________                                        water             89.264                                                      monosodium phosphate                                                                            0.269                                                       trisodium phosphate                                                                             2.230                                                       sodium tetradecyl sulfate                                                                       8.237                                                       ______________________________________                                    

Any developer solutions which satisfactorily removes the nonimage areasof the photosensitive layer after exposure while retaining the imageareas may be used. The selection of developer is well within the abilityof the skilled artisan.

The process of lamination, substrate separation, exposure, anddevelopment can then be repeated whereby another photosensitive elementhaving a different color is laminated to the same receiver sheet overthe previously formed image. In the usual case, four colored layers areemployed to produce a full color reproduction of a desired image. Theseare cyan, magenta, yellow and black.

The following nonlimiting examples serve to illustrate the invention.

EXAMPLE 1

Four photosensitive solutions of cyan, yellow, magenta, and black areproduced according to the negative-working photosensitive formulationsas described above. The pigment is introduced as a dispersion of methylethyl ketone, Scripset 540, and the appropriate pigment. The solutionsare coated and dried separately to the required optical density onto 3mil Melinex 516 polyester films as the temporary substrates. The surfacedensities are roughly 1.3 g/m² for cyan, 0.9 g/m² for yellow, 1.8 g/m²for magenta, and 1.2 g/m² for black. The adhesive solution, inparticular adhesive formulation I as described above, is coated on topof the photosensitive layers and dried to a surface density of 12 g/m².The yellow composite is then laminated at 90° C. with the adhesive sideonto either side of a 7 mil Melinex 3020 polyester receiver sheet. The516 temporary substrate is peeled away after lamination, leaving theadhesive and photosensitive layers on the receiver sheet. The yellowphotosensitive layer is then exposed to actinic light through aphotographic separation for the yellow color. The receiver sheet withthe exposed yellow layer is then immersed for 15 sec in the developerdescribed above at 27° C. with gentle pad rubbing on the photosensitiveside. The nonexposed, yellow areas are thereby washed off and theexposed areas remain during development. If no exposure is given, thenall of the photosensitive layer and 6% of the adhesive layer is removedduring development. After development, the imaged material is rinsed andthen dried. The magenta composite is then laminated as before onto theimaged, yellow side of the receptor sheet. The temporary substrate isremoved as before. The magenta layer is then exposed through the magentaseparation. It is then processed as with the yellow. The magenta isfollowed in a like manner by cyan and then by black to give a four colorimage which is an accurate representation of the original from which theseparations are prepared.

The background stain, as measured as the optical density gain in thenonexposed, nonimage areas of the four color proof, is 0.02 for the cyanfilter, 0.03 for the yellow filter, 0.02 for the magenta filter, and0.02 for the visible filter. Samples made without the Gantrez AN-119 inthe adhesive have an extremely high background stain of 0.46 for cyan,0.24 for yellow, 0.33 for magenta, and 0.35 for visible. Values lessthen 0.05 are generally acceptable for a color proof.

EXAMPLE 2

Four photosensitive solutions of cyan, yellow, magenta, and black areproduced according to the positive-working photosensitive formulationsdescribed above. The pigment is introduced as a dispersion of methylethyl ketone, Scripset 540, and the appropriate pigment. The solutionsare coated and dried separately to the required optical density onto 3mil Melinex 516 polyester films as the temporary substrates. The surfacedensities are roughly 1.2 g/m² for cyan, 1.4 g/m² for yellow, 2.0 g/m²for magenta, and 1.0 g/m² for black. The adhesive solution, inparticular adhesive formulation II as described above, is coated on topof the photosensitive layers and dried to a surface density of 8 g/m².The yellow composite is then laminated at 80° C. with the adhesive sideonto either side of a 7 mil Melinex 3020 polyester receiver sheet. The516 temporary substrate is peeled away after lamination, leaving theadhesive and photosensitive layers on the receiver sheet. The yellowphotosensitive layer is then exposed to actinic light through aphotographic separation for the yellow color. The receiver sheet withthe exposed yellow layer is then immersed for 15 sec in the developerdescribed above at 27° C. with gentle pad rubbing on the photosensitiveside. The exposed yellow areas are thereby washed off and the nonexposedareas remain during development. If a uniform, blanket exposure isgiven, all of the photosensitive layer and 14% of the adhesive layer isremoved during development. After development, the imaged material isrinsed and then dried. The magenta composite is then laminated as beforeonto the imaged, yellow side of the receptor sheet. The temporarysubstrate is removed as before. The magenta layer is then exposedthrough the magenta separation. It is then processed as with the yellow.The magenta is followed in a like manner by cyan and then by black togive a four color image which is an accurate representation of theoriginal from which the separations are prepared.

The background stain, as measured as the optical density gain in theexposed, nonimage areas of the four color proof, is 0.03 for the cyanfilter, 0.03 for the yellow filter, 0.04 for the magenta filter, and0.03 for the visible. Samples made without the Carboset 525 in theadhesive have a high background stain of 0.14 for cyan, 0.10 for yellow,0.13 for magenta, and 0.13 for visible.

What is claimed is:
 1. A photosensitive element which comprises, inorder:i) a substrate having a release surface; and ii) a single, coloredphotosensitive layer on said release surface, which photosensitive layercomprises in admixture a light sensitive, negative-working diazoniumsalt or positive-working naphthoquinone diazide compound in an amountsufficient to photosensitize the layer; a resinous binder composition inan amount sufficient to bind the layer components into a uniform film,which composition contains a major amount of at least one resin selectedfrom the group consisting of a vinyl acetal polymer and a styrene/maleicanhydride copolymer half ester; and at least one colorant in an amountsufficient to uniformly color the layer; and iii) a nonphotosensitiveadhesive layer in direct contact with said photosensitive layer, whichadhesive layer comprises greater than 50 percent of one or morethermoplastic polymers, and one or more developing aids capable ofpromoting the partial removal of the adhesive layer with a developer, isonly partially soluble in a developer, nontacky at room temperature, andcan be transferred at temperatures between 60° C. and 180° C.
 2. Theelement of claim 1 wherein said substrate comprises polyethyleneterephthalate.
 3. The element of claim 1 wherein said substrate has amatte surface.
 4. The element of claim 1 wherein said release surface onsaid substrate comprises polyvinyl alcohol.
 5. The element of claim 1wherein said naphthoquinone diazide in the photosensitive layercomprises the ester of bis-(3-benzoyl-4,5,6-trihydroxy phenyl)-methaneand 2-diazo-1-naphthol-5-sulfonic acid.
 6. The element of claim 1wherein said diazonium salt in the photosensitive layer comprises thepolycondensation product of 3-methoxy-4-diazo-diphenyl amine sulfate and4,4'-bis-methoxymethyl-diphenyl ether precipitated as mesitylenesulfonate.
 7. The element of claim 1 wherein said photosensitive layerfurther comprises one or more ingredients selected from the groupconsisting of plasticizers, stabilizers, antistatic compositions, uvabsorbers, surfactants, optical brighteners, and inert fillers.
 8. Theelement of claim 1 wherein the photosensitizer is present in thephotosensitive layer in an amount of from about 5 to about 70 percent byweight.
 9. The element of claim 1 wherein the colorant is present in thephotosensitive layer in an amount of from about 5 to about 50 percent byweight.
 10. The element of claim 1 wherein the binding resin is presentin the photosensitive layer in an amount of from about 10 to about 80percent by weight.
 11. The element of claim 1 wherein the adhesive layerhas a coating weight of from about 3 to about 30g/m².
 12. The element ofclaim 1 wherein the adhesive layer further comprises one or moreingredients selected from the group consisting of uv absorbers,antistatic compositions, resins, plasticizers, and optical brighteners.13. The element of claim 11 wherein the adhesive layer comprises one ormore thermoplastic polymers selected from the group consisting of vinylchloride, vinyl butyral, acrylic, ethylene, and phenolic resins.